In these days of rapidly increasing urban populations and exploding resource demand in developing regions, it is ever more important to conserve our natural resources. One of our most precious resources is fresh water. Water is used in many applications, both in the home and in industry, not to mention the service sector. One important common use for water is in the washing of garments and materials, typically in a washing machine. However, an improperly maintained or adjusted washing machine is capable of wasting a great deal of water in short period of time, leading to increased costs and wasted resources.
In particular, improper operation of the drain valve or pump, can result in excessive water use during the wash cycle due to water leaking from a drain valve that is not fully closed. The improper operation of the drain valve or pump can also result in laundry cycles that require a greater period of time to complete the filling and draining process which will result in greater energy use than is necessary. The improper operation of the drain valve or pump may be due to an inherent failure of the drain valve or pump or it may be the result of a foreign object that has become lodged in the pump or drain valve.
Such foreign objects may be introduced into the machine with the laundry or may be parts of the laundry itself (fabric, zippers, bra wires, rubber backing from floor rugs, etc.). Foreign objects that may be inadvertently added with the laundry include coins, nails, screws, pencils, keys, etc. Whatever the source and exact object, the foreign object may become lodged in the valve or pump, or may otherwise result in a malfunction of the drain valve or pump which will prevent the drain valve or pump from opening or closing fully. In addition to the introduction of such foreign objects, other causes of drain or valve malfunction also exist. For example, the drain valve or pump could also malfunction as a result of normal wear and tear and the deterioration of the components of the drain valve or pump.
As a result of the above mentioned problems, the drain valve or pump may remain partially open during one or more portions of the machine cycle in which water is intended to be retained in the machine. This condition will cause water to leak from the washing machine, dramatically increasing the volume of water used by the machine. Also, the foreign object or other condition may prevent the water from draining or pumping optimally from the machine during one or more portions of the machine cycle in which the water is intended to be drained or pumped from the machine. This can cause machine cycles to take much longer and use more energy than necessary.
The above-described problems may not be easily noticed by the machine user or the owner/servicer of the equipment. In order to determine if there is a malfunction, or if there is a foreign object lodged in the drain or pump, the owner/servicer would be required to spend considerable time and effort disconnecting power from the machine and removing the machine outer panels and drain hoses in order to examine the drain or pump to determine if it was malfunctioning.
One technique to attempt to overcome these problems involved monitoring the length of time required to fill the machine with water, or to drain water from the machine, and sounding an alarm if the time was greater than a programmed “alarm time.” However, this technique is generally only useful for detecting a condition where water pressure is extremely low or non-existent resulting in the machine never reaching the desired water level. If the machine reached the desired water level prior to the alarm time, the controller accepted this without generating an error condition. Water leaks in the machine were not detected.
Similarly, the drain alarm error condition is generally only useful for detecting a nearly or completely plugged drain that results in a very long drain time or a non-draining condition. A partially obstructed drain or pump which is able to evacuate the water prior to the expiration of a drain alarm time would not be detected.